Insulated threshold



Oct. 17, 1967 J. M. KESLER 3,346,994

INSULATED THRESHOLD Filed Aug. 20, 1955 INVENTOR ATTORNEYS United States Patent 3,346,994 INSULATED THRESHOLD John M. Kesler, Lafayette, Ind., assignor to National Homes Corporation, Lafayette, Ind. Filed Aug. 20, 1965, Ser. No. 481,244 8 Claims. (Cl. 49-470) ABSTRACT OF THE DISCLOSURE A threshold formed of three extruded aluminum shapes and a strip of insulating material, two of the shapes being interlocked and defining that part of the threshold outwardly of the bottom of a door and exposed to outside temperatures. The third shape being mechanically interlocked with the insulating material which in turn is interlocked with the first two shapes, the third shape extending inwardly from the door thermally insulated from the first two. A strip of resilient insulating material is carried by the bottom edge of the door in position to sealingly engage the threshold.

Background of the invention The present invention relates to a metal threshold construction wherein outdoor portions are insulated from indoor portions.

This invention relates to thresholds, particularly for use in a doorway having a door hinged therein.

It has long been recognized that the formation of a threshold structure of metal is highly desirable to provide dimensional stability and long-wearing characteristics. However, the use of metal for thresholds presents a number of problems, such as high cost, difliculty of fabrication, and the fact that metal is a good conductor of heat and, in the case of a one-piece structure, the entire threshold, even those portions exposed to the interior of a room, get very cold in winter when the door with which it is used opens to the outside.

It has long been proposed to use extruded aluminum thresholds, which reduces the cost to a practical value and permits manufacture by rapid and low-cost techniques. However, aluminum is such a good conductor of heat that such a threshold used on an outside door results in considerable heat loss and the inner portion or part exposed to the interior of the house getting very cold in the wintertime and often moisture from the dwelling condenses on those cold portions and may even form frost, which condensation is not only unsightly but damaging to floors, carpets, and the like.

Summary of the invention The invention resides in a threshold of metal parts, for example extruded aluminum shapes, which are interlockingly engaged with thermal insulating material and arranged so that the portions exposed on the outside of a door are thermally insulated from the portions inside the door. One of the parts defining a base has a channel in which edge flanges of the other parts, which constitute trim plates, slidably engage in the channel wherein the inside trim plate is insulated from the other parts. A doorcarried strip of insulating material sealingly engages adjacent edges of the trim plates when the door is closed, over the threshold.

It is, therefore, an object of this invention to provide a metal threshold wherein the inner and outer portions thereof are fully insulated from each other.

Another object is to provide a threshold of the type set forth formed of readily extrudible and inter-locking shapes and requiring no special tools for assembly.

Still another object is to provide such a threshold which further includes means for supporting a Weatherstripping device for an auxiliary door, such as a storm or screen door.

A further object is to provide such a threshold readily adaptable for cooperation with a Weatherstripping device on the door itself.

A still further object is to provide such a threshold that is simple and economical to construct yet sturdy and reliable in operation.

Additional objects and advantages will become apparent to those skilled in the art as the description proceeds with reference to the accompanying drawings wherein:

FIG. 1 is a vertical sectional view through the lower portion of a doorway showing the present invention in place therein;

FIG. 2 is a fragmentary perspective view of the base plate of the present invention;

FIGS. 3 and 4 are, respectively, fragmentary perspective views of outer and inner trim plates; and

FIG. 5 is a fragmentary perspective view of a strip of insulating material comprising a portion of the present invention.

In FIG. 1, a sill or frame member 2, usually of wood, defines the bottom of a doorway 4 in which a door 6 is hinged in the usual manner. The threshold structure is designated generally at 8 and comprises a base plate member 10 secured to the sill 2 in any suitable manner, such as by means of screws 12. The base plate 19 includes a generally horizontal base plate portion 14 lying on the upper surface of the sill 2. The inner edge of the base plate portion 14 extends upwardly to define an edge flange 16 and integral with the upper edge thereof is an upwardly facing channel having side walls 18 and 20. The upper edges of the side walls 18 and 20 terminate in inwardly directed ribs 22 and 24, respectively. It is to be understood that the base plate 10 is of elongated shape and extends across the doorway from side to side thereof, as do all of the parts to be described herein.

A rib 25 is formed integrally on the upper surface of base plate 14 and is undercut as at 26. The rib extends parallel to the flange 16 but spaced therefrom, as shown. An outer trim plate 28 is provided with a downwardly extending flange 30 at its inner edge, which flange extends downwardly into the outer portion of the upwardly facing channel referred to and a terminal rib 32 interlockingly engages under the rib 22 to lock the trim plate in position. From the upper edge of flange 30 the trim plate 28 extends generally outwardly and downwardly to a terminal flange 34 at its outer edge. The terminal flange 34 engages in the undercut 26 of rib 25. While the parts are preferably of extruded aluminum, it will 'be readily apparent that the trim strip 28 and base plate 10 may first be cut to the desired length and then assembled by longitudinal relative sliding in an obvious manner wherein the parts are interlocked as described. When the threshold is then mounted in the doorway, relative longitudinal movement between those parts is prevented and they are held in firm assembled relationship.

Within the upwardly facing channel referred to is a body of thermal insulating material 36. The body 36 is provided with spaced projecting ribs 38 engaging the inner Wall 20 of the channel and the upper one of which engages :under the rib 24. The width of the strip 36 is sufficient so that spaced ribs 39 on its outer face bears resiliently against the flange 30 of the trim strip 28. The body 36 is further provided with an upwardly open but undercut channel 40 (see FIG. 5) into which a second flange 42 extends.

The flange 42 is provided with a longitudinal head 44 at its lower edge, which bead interlocks with the under cut portion of the channel 40 and the parts are all thus firmly locked in position. Extending inwardly and downwardly from the upper edge of flange 42 is an inner trim strip 46 which extends downwardly into contact with the sill 2 and is held in place by means of screws 48 or the like. It is to be noted that the trim strip 46, along with its flange 42, do not at any point make direct contact with any portion of the base plate 10 or outer trim strip 28 and it is thus completely and thermally insulated therefrom. The body 36 of insulating material may be any suitable material but applicant has found a vinyl resin material to be very satisfactory. This material not only provides good thermal insulation but is also resistant to weather and has suflicient resilience to permit a snug interlocking of the parts to hold them in tight assembled relationship.

It is further to be noted that the inner portion of the trim strip 28 and the outer portion of trim strip 46 are arranged in generally coplanar relation to define a substantially horizontal crest surface for the threshold.

As is evident from the drawings, the upwardly facing channel containing the insulating material 36 is within the doorway 4 and underlies the lower edge 50 of the door 6 when the latter is closed. The door 6 is provided with an extruded strip 52 secured thereon and formed to define a drip flange 54 and channels 56. A resilient Weatherstripping strip 58 is provided with edge beads interlocking with the channels 56 and, as shown, the strip 58 is bowed downwardly and resiliently engages the adjacent portions of both trim strips 28 and 46 when the door is closed. From the above description it will be apparent that when the door 6 is closed no portion of trim strip 46 is in heat-conducting relation to either the base plate 10 or the outer trim strip 28, and that no portion of the trim strip 46 is exposed to outside temperatures. Thus, trim strip 46 is exposed only to the temperature within .the building and is completely insulated from ambient outdoor temperatures and thus achieves the objectives of the invention.

The base plate 10 is shown extending outwardly beyond the illustrated confines of the doorway 4 and is configured to define an outer edge surface 60, in addition to defining an attaching portion or flange 62. The outer edge portion 60 is provided with an undercut groove 64 extending thereacross and in which a suitable resilient strip 66 is positioned. The strip 66 thus serves as a Weatherstripping for engagement with an auxiliary door,

suchas a storm or screen door, not shown.

While a single specific embodiment of the invention is shown and described herein, the same is merely illustrative of the principles of the invention and other forms may be resorted to within the scope of the appended claims.

I claim:

1. A threshold for a doorway, comprising: a generally horizontal metal base plate extending across the bottom of said doorway; an upwardly facing channel at the inner edge of said base plate, within said doorway; an outer metal trim plate having a first edge flange extending downwardly into the outer edge of said channel, said outer metal trim plate extending downwardly and outwardly from said flange to said base plate; an upwardly 0 open channel shaped body of insulating material in said upwardly facing channel adjacent said first flange; and an inner metal trim plate having a second downwardly directed flange at its outer edge seated in said upwardly open channel, said outer metal trim plate extending downwardly and inwardly from said second flange to the bottom of said doorway, saidrinner trim plate being free of direct contact with said base plate, said upwardly facing channel and said outer trim plate.

2. A threshold as defined in claim 1 wherein said base plate is provided at its inner edge, with an upwardly extending integral flange; said upwardly facing channel being integral with the upper edge of said flange.

3. A threshold as defined in claim 1 wherein said base plate and said upwardly facing channed are provided with oppositely facing parallel undercut grooves extending across said doorway; said outer trim plate having longitudinal ribs slidably engaging in said grooves for securing said trim plate in position.

4. A threshold as defined in claim 1 wherein said second downwardly directed flange is provided with means interlockingly engaging said body of insulating material and said body of insulating material is provided with means interlockingly engaging said upwardly facing channel.

5. A threshold as defined in claim 1 wherein said upwardly facing channel includes spaced upstanding side walls; each side wall having an inwardly directed rib extending along its upper edge; said ribs respectively inter-v lockingly engaging said first flange and said body of insulating material.

6. A threshold as defined in claim 1 wherein said base plate extends outwardly of said doorway then downwardly to define an outwardly facing edge surface; an undercut groove in said surface and extending across said doorway; and a resilient strip of material in said groove and projecting from said edge surface for yieldable engagement with an auxiliary door.

7. A threshold as defined in claim 1 including a door carried strip of resilient insulating material overlying said upwardly facing channel and substantially sealingly engaging the adjacent edge portions of both said trim plates.

8. A threshold as defined in claim 7 wherein said adjacent edge portions of said trim plates are substantially coplanar to define a substantially horizontal upper surface for said threshold below said door-carried strip.

References Cited UNITED STATES PATENTS 1,873,143 8/1932 Olson. et al. 49470 2,167,958 8/1939 Oftedal et 'al. 49-470 X 3,061,896 11/1962 Wahfeld 49-469 3,079,652 3/1963 Wahfeld 49--469 3,114,180 12/1963 Riedl 49-468 3,273,287 9/1966 Pease 49-47O X FOREIGN PATENTS 912,452 12/1962 Great Britain.

EARL J. WITMER, Primary Examiner.

P. C. KANNAN, Assistant Examiner. 

1. A THRESHOLD FOR A DOORWAY, COMPRISING: A GENERALLY HORIZONTAL METAL BASE PLATE EXTENDING ACROSS THE BOTTOM OF SAID DOORWAY; AN UPWARDLY FACING CHANNEL AT THE INNER EDGE OF SAID BASE PLATE, WITHIN SAID DOORWAY; AN OUTER METAL TRIM PLATE HAVING A FIRST EDGE FLANGE EXTENDING DOWNWARDLY INTO THE OUTER EDGE OF SAID CHANNEL, SAID OUTER METAL TRIM PLATE EXTENDING DOWNWARDLY AND OUTWARDLY FROM SAID FLANGE TO SAID BASE PLATE; AN UPWARDLY OPEN CHANNEL SHAPED BODY OF INSULATING MATERIAL IN SAID UPWARDLY FACING CHANNEL ADJACENT SAID FIRST FLANGE; AND 